This generally to handles for pressurized hoses and more particularly to handles for blast hoses.
The application of pressurized material such as gas or liquid (sometimes referred to as medium) is well known and has been used for well over a century for such things as the removal of damaged paint and other coatings, removal of rust, impregnation of chemicals into substrates, cutting of substrates, and the conveying of selected materials for a broad variety of purposes.
Basically, the application requires a medium or a medium which is mixed with a selected material (sometimes referred to as media) to be conveyed under pressure The medium or a mixture of the medium and selected media (such as a chemical or abrasive particles) can be used to treat, cut, or abrade a surface or target.
This basic approach has not changed since its inception more than a century ago; however, the surfaces or substrates to which the applications may apply have changed drastically. There now are topcoats and underlying substrates, such as plastics, composites, thin or exotic metals, and other surfaces, where this technology can be used in a beneficial manner. These new surfaces or substrates require the exercise of a great deal of care and skill to preclude damaging the surface, substrate, or other target.
Because of the care that must be taken, many inventions have focused on providing a handle which gives the operator greater mechanical control of the blasting head. These include U.S. Pat. No. 3,069,812, entitled "Sand Blasting Nozzle" issued Dec. 25, 1962, to Shelton-V; and U.S. Pat. No. 2,369,576, entitled "Blast Gun", issued Feb. 13, 1945, to Keefer.
In both of these situations, the handle provides for fixed mechanical control of the blast hose. The handle is attached to the end of the hose and extends downward in a "pistol grip" arrangement.
Although this does provide for good positive relationship between the operator's movement and the nozzle of the hose, the natural torque of the hose, accentuated due to the pressurization process, forces the operator to constantly "fight" or strain against the hose torque. This accelerates the operator fatigue problem and reduces the operator's responsiveness to variations in substrates or changes in target conditions. This can cause damage to the substrate or target.
Substrate material changes are very common in the modern world. A coated material that may appear to be of a common composition may have underlying areas of dissimilar material interposed throughout, and which are masked by a coating. A pressurized application of a medium or a mixture of medium and media that works well on one target, can cause damage when applied to other surfaces, substrates, or targets.
To compensate for this, several advancements in the technology have tried to place the mixing of the material at the handle. These advancements include U.S. Pat. No. 4,628,644, entitled "Abrasive Material Spraying Apparatus" issued Dec. 16, 1986, to Somers; U.S. Pat. No. 2,526,403, entitled "Abrasive Gun" issued Oct. 17, 1950, to Paasche; and U.S. Pat. No. 2,577,465, entitled "Sand Blast Gun" issued Dec. 4, 1951, to Jones et al.
In all of these applications, the added weight of the sand, abrasive material, or other material to be applied, causes even further operator fatigue since this weight must be swept and moved with the head of the pressurized hose.
In a commercial setting, these solutions are inoperable since the mass of material to be applied is so great, the operator could not physically move it. When a more manageable amount is placed at the spray head, the operator is forced to constantly stop and refill. This significantly handicaps the work through-put.
Another major concern related to the conveyance of medium or a mixture of medium and media under pressure is the safety issue. Operating a high pressure hose is very dangerous. Should something go wrong with the system or should even a minor accident occur such as an operator stumbling, the released pressure hose can cause damage to products and facilities as well as injure personnel.
Because of this, "dead-man" switches such as those described in U.S. Pat. No. 2,837,874, entitled "Sand Blasting Apparatus" issued June 10, 1958, to Hunter; or U.S. Pat. No. 2,753,664, entitled "Abrasive Blasting System" issued July 10, 1956, to Garver, were developed. In both situations, the dead-man switch is arranged at the handle. This is attached to the hose so to have normal operation, the operator depresses the dead-man switch. When the switch is depressed, the hose is pressurized and works normally. When the operator releases the switch, either intentionally or unintentionally, the hose cannot be pressurized. This eliminates the possibility of the hose being released from the operator's grasp while still being pressurized.
As with the aforementioned pistol grip, the dead-man switch forces the operator to maintain a fixed grip on the hose. This also forces the operator to fight the naturally occurring and significant torque, producing operator fatigue. Because of the fatiguing nature of the work, the operator cannot operate efficiently and therefore must take numerous breaks.
It is clear from the forgoing that an efficient handle and pressure application system does not exist which permits: (i) the optimal use of a pressurized hose system; and (ii) allows proper control of pressurized hose systems to address the various topcoats, substrates, and other targets encountered.